Diesel-electric vehicle with automatic field weakening of the driving motors



June l, 1948. v 0, SCHLPFER 2,442,665

DIESEL-ELECTRIC VEHICLE wTTH AUTOMATIC FIELD WEAKENING 0F THE DRIVING MOTORS Filed March 7, 1945 lNvEp'x-ron USC/QR SCHL HPFER BY @W' a ATTORNEYS Patented June 1, 1948 DIESEL-ELECTRIC VEHICLE WITH AUTO- MATIC FIELD WEAKENING F THE DRIV- ING MOTORS osm schlauer, winterthur, switzerland, as!

signor to Sulzer Frres terthur, Switzerland Socit Anonyme, Win- Application March '1, 1945, Serial No. 581,474 In Switzerland March 9, 1944 The invention relates to control apparatus for i moves completely over the contacts, a locking dea Diesel-electric power plant used for the propulsion of a vehicle. In particular, it relates to control apparatus of the type in which a servomotor adjusting the weakening of the fields of the driving motors is controlled in accordance with the field regulator adjusting the excitation of the main generator to maintain a predetermined constant load on the Diesel engine at a constant speed, and in which the regulators for regulating the elds of the main generator and of the driving motors are designed for instance as astatic regulating members and the control member of the driving -motor regulator has in its closed position so great a degree of overlapping that the field regulator of the generator can move, in the neighbourhoodofthe position for short-circuited resistance, without bringing this control member out of its closed position, over lsuch a large range that the change of load presenting itself within this range is at least as great as the change of load caused by the'greatest step'of the field weakening.

According to this invention the regulator for the fields of the driving motor is provided with a device which ensures that the controlling switch will come to rest only when it has moved into a position in which it is completely over a contact.

The generator field regulator in control apparatus of the type described above will in practice not come to rest for some time. It is thus of no importance if the contact member on the lever moves only a little way over a fixed contact point as the high specific contact loading which thus arises cannot result in excessive heating of the parts. This is not true, however, in the case of theregulating switch for the driving motor fields. When this switch has once cut in a step, it may be a long time until it cuts it out again or until it moves on to another step, as in the meantime the regulator for the generator field again takes over the regulation as described in the specification of the earlier application of Oscar Schlpfer, Serial No. 554,892, filed September 20, 1944, now Patent No. 2,433,628, December 30, 1947. The switch may thus remain for a long time on one step so that, particularly when the loading of the contact is great, measures must be taken to prevent excessive contact heating as a result of the contacts being insufllciently covered.

These disadvantages are eliminated according to the present improvement by providing the regulating switch for the driving motor fields with a device which ensures that the switch vice or anotched disc being used to ensure that the regulating switch' can only come to rest in definite positions. Since the contact path is then better utilised from the aspect of loading, the current load distributed over the whole surface of the contact may be increased. As a contact is broken rapidly land completely, the power to be switched can be increased for the contact and it is thus possible to manage with a smaller number of steps.

An embodiment of the invention is shown diagrammatically in the accompanying drawing, and in this the complete covering of the separate contacts by the field weakening switch is ensured by a locking mechanism. In the drawing Figure l is a diagram of the system while Figures 2 and 3 are detail diagrams of the locking mechanism.

As described in the specification of the earlier application Serial No. 554,892, an internal combustion engine I drives a main generator 2 and an auxiliary generator 3. The vehicle has a driving motor 4, apparatus 5 serving for reversing the direction of travel and for interrupting the main cir-cuit, a governor 6 for the engine with y Instead of the field weakening switch being in the form of a lever as shown in application No. 554,892, the field weakening switch is here shown as a drum-shaped switch 6I), which is driven by an electric motor 5B through gearing 59. According as the switch 53, which is operated by the piston I4 of the generator field regulator I2, connects the contact 54 or 55 with the field 51, respectively, or 58 of the motor 56, so will the contact drum 69 move to the right over the ccntacts 'I3- 19 so as to decrease the resistance 39, or to the left so as to increase the resistance, As in application No. 554,892, a. contactor 34 ensures that the field weakening is only possible at high voltage of the generator.

The partsso far described represent only a possible arrangement of the devices proposed in application No. 554,892. The further parts embody the present invention which has advantageous features which constitute a specific improvement over the earlier arrangement. They consist individually in a notched disc with a locking bar` 66, the motion of which is controlled by magnets 61 and I0 and springs 69 and 12. The contacts 6I-64 arranged on the drum load on the engine I.

'seiten so; together with the cantata sa' and 1|- on the magnets"61and16, ensure that the motor 56 can only come to rest` when the drum switch 60 is in a position-in which the Ytongue 66' on the locking bar 66 engages a notch in the disc 65.

The contacts 6I64 and .68, 1I are not indispensable to the device here proposed and are only I necessary when there is a danger that the inertia of the drum 60and of the mass rotating with it is too small, after the contact 53 is switched out,

to turn the notched disc 65 far enough Iorthe locking bar 66 to fall into the next notch 65'. The operation of the device, in so far as it l cannot be gathered from the specication of the earlier application SeriaifNo- 554,892, is as follows:

As long as the eld regulating piston I4 has not reached the neighbourhood of the position B for short-circuiting the resistance I1, the switch 53 stands ron the contact 55 and the field 58 of the motor 56 is connected to the source of the control current. At the samev time the magnet 10 is excited (Figure 3), and pushes away thelocking bar 66 in opposition to the pressure of the spring 12, so that the notched disc 65 can turn. In the position shown in Figure 1 the motor 56 has already turned the drum switch 66 circuit between the contacts 13 and 14 is interrupted. A` limit switch 80 rotated with the drum switch 60 has also interrupted the current through field 58 of the motor 56 in this position.

VThe driving motor 4 now works with full field.

Ifthe iield regulating piston I4 approaches the position B, for short-circuiting the resistance I1 (position B), the switch 53 leaves the contact 55 and later goes over on to the contact 54. The

iield 58 is switched out and the ileld 51 switched in. The motor 56 turnsin the other direction after the magnet 61 has been excited and has pushed away the locking bar 66 in opposition to the pressure of the spring 69 (Figure 2). Provided that the minimum operating tension of the contactor 34 is reached, the element 60' closesv the field weakening circuit at the contacts 13 and 14. l

'Ihe drivingmotor current increases as a result of the fieldV weakening, and thus also the Inuenced by the gover-i nor 6, the eld regulating piston I4 moves downwards, so that the current from the switch V53 to the contact 54 is interrupted. Without the contacts 6I64 and 18419, the iield 51 and the magnet 61 would thus be without current, and, if

' the parts in connection with the motor 56 have sufficient kinetic energy, the drum switch 60 turns .f-"tacting piece 6I has covered these contacts. The

motor 56 thus runs further in any case until the contacting piece 6I interrupts'the circuit immediately before the position I. Y

The field regulating piston I4 now goes back until the overloading started by the rst eld weakening step is equalised. According to the earlier application Serial No. 554,892 the resistances I1 and 38 are so chosen relatively to each other that the piston I4 must not go back at any 4 ield weakening step far enough to cause switch 53 to cover the contact 55.

If the generator current decreases again during the further acceleration of the vehicle. the piston I4 rises. When the contact 54 is again reached, the same process as previously described for the transition from step'II tov step I now takes place for the transition from step Ito step II.

and afterwards for the steps III and IV, until iinally when the step IV is reached limit, switch j 80 rotated with the drum 60 cuts out the circuit through ileld 51 of the motor '56 if the switch 53 should remain on the contact 54.

Ii the drum switch 60 is on one of the steps I-IV and the switch 53 goes back on to the contact 55, the eld 58 is switched in. The magnet 10 then pushes away the locking bar 66 (Figure 3) and the drum switch 60 moves to the left, whereby the field weakening of the driving motor 4 and thus the load on theengine I decrease. The governor 6 now causes the piston I4 to rise again and interrupts the 4connection between switch 53 and contact 55. The drum switch 60, however, still turns into the next position, as the magnet 10 and the ileld 58 are provided with current through the contacts 18 to 19, one of the contacts 6I-64 and'the contact completely to the left, so that the field weakening 1I. The switching back of the drum switch 6|) step by step thus takes place in principle in exactly the same'way as has been described for forward switching.

I claim 1. In Diesel-driven electrical apparatus of the type comprising a Diesel engine, a speed governor driven by said engine, a generator driven by said engine, a field resistance for altering the field of said generator, a rst servo-regulator for setting said field resistance, means connecting said speed governor to said rst servo-regulator whereby the field resistance changes when the speed of said engine changes, the effect being that the load on said engine is kept constant, at least one electric motor driven by current from said generator, a further resistance for connecting in parallel to the iield of each of said motors, switch means vfor each of said further resistances, a second servo-regulator for altering the switchedin partof each of, said further resistances and means connecting said servo-regulators operatively with each other whereby said second servoregulator, when said iirst servo-regulator has cutout the maximum of saideld resistanceyis actuated with an increase in speed of said engine in the sense of a'decrease in said further resistances and vwith a reduction in speed of said engine in'4 one of said resistance steps from the iield circuit of the motor associated therewith, said drum being controlled by said second servo-regulator,

and there is provided a notched piece for bringing said contact drum to rest only when said main contact areas are in full contact or out of contact. I

2. In Diesel-driven electrical apparatus according to claim 1, a pawl engaging in the Athe 'n' notched piece when the contact drum ls in a. position in which the main contact areas are in full contact or out of contact, and means for withdrawing sad pawl from engagement with said notched piece when the second servo-regulator is being influenced by the rst servo-regulator.

3. Diesel-driven electrical apparatus according to claim 1in which the second servo-regulator includes an electric servomotor, a pawl engaging in the notched piece when the contact drum is in a position in which the main contact areas are in full contact or out of contact, and at least one solenoid wired to be energized by current activating said servomotor and arranged to withdraw said pawl from engagement with said notched piece when energized. i

4. Diesel-driven electrical apparatus according to claim 1 in which the second servo-regulator includes an electric servomotor, a pawl engaging in the notched piece when the contact drum is in a position n which the main contact areas are in full contact or out of contact, at least one solenoid wired to be energized by current activating said servomotor and arranged to OSCAR SCHLAPFER..

REFERENCES CITED The following references are of. record in the file of this patent:

UNITED STATES PATENTS Number Name Date 786,376 Nilson Apr. 4, 1905 1,730,786 Rosenthal Oct. 8, 1929 1,900,706 Godsey Mar. 7, 1933 2,131,527 Sousedik Sept. 27, 1938 2,145,611 Schlaepfer Jan. 31, 1939 2,256,294 Schlaepfer Sept. 16, 1941 2,424,310 Frisch July 22, 1947 

